TURBINE ENGINE ASSEMBLIES
Turbine engine assemblies including a turbine engine assembly having a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned, wherein the combustion section comprises a generally annular case having inner and outer walls, a heat exchanger comprising multiple passages in proximity to at least one of the inner and outer walls, with the passages arranged about at least a portion of the case and in fluid communication with each other such that fluid may flow through the passages and a cryogenic fuel system having a cryogenic fuel tank with a supply line coupled to one of the passages, wherein cryogenic fuel may be supplied from the cryogenic fuel tank, through the supply line, to the passages of the heat exchanger, where the fuel in the passages may be heated by the combustion section. The heat exchanger may be a single or multistage vaporizer.
This application claims the benefit of U.S. Provisional Patent Application Nos. 61/746,847, 61/746,855, 61/746,872, 61/746,882, 61/746,915, and 61/746,673, all filed on Dec. 28, 2012, and all of which are incorporated herein in their entirety.
BACKGROUND OF THE INVENTIONThe technology described herein relates generally to aircraft systems, and more specifically to aircraft systems using dual fuels in an aviation gas turbine engine and a method of operating same.
Certain cryogenic fuels such as liquefied natural gas (LNG) may be cheaper than conventional jet fuels. Current approaches to cooling in conventional gas turbine applications use compressed air or conventional liquid fuel. Use of compressor air for cooling may lower efficiency of the engine system.
Accordingly, it would be desirable to have aircraft systems using dual fuels in an aviation gas turbine engine. It would be desirable to have aircraft systems that can be propelled by aviation gas turbine engines that can be operated using conventional jet fuel and/or cheaper cryogenic fuels such as liquefied natural gas (LNG). It would be desirable to have more efficient cooling in aviation gas turbine components and systems. It would be desirable to have improved efficiency and lower Specific Fuel Consumption in the engine to lower the operating costs. It is desirable to have aviation gas turbine engines using dual fuels that may reduce environmental impact with lower greenhouse gases (CO2), oxides of nitrogen—NOx, carbon monoxide—CO, unburned hydrocarbons and smoke.
BRIEF DESCRIPTION OF EMBODIMENTS OF THE INVENTIONIn one aspect, an embodiment of the invention relates to a turbine engine assembly including a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned, wherein the combustion section comprises a generally annular case having inner and outer walls, a heat exchanger comprising multiple passages in proximity to at least one of the inner and outer walls, with the passages arranged about at least a portion of the case and in fluid communication with each other such that fluid may flow through the passages, and a cryogenic fuel system having a cryogenic fuel tank with a supply line coupled to one of the passages, wherein cryogenic fuel may be supplied from the cryogenic fuel tank, through the supply line, to the passages of the heat exchanger, where the fuel in the passages may be heated by the combustion section.
In another aspect, an embodiment of the invention relates to a turbine engine assembly having a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned, a cryogenic fuel system having a cryogenic fuel tank with a supply line, and a multistage vaporizer comprising at least one passage fluidly coupled with the supply line such that cryogenic fuel supplied from the cryogenic fuel tank flows through the at least one passage of the multistage vaporizer, where the fuel in at least one passage may be heated.
The technology described herein may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:
Referring to the drawings herein, identical reference numerals denote the same elements throughout the various views.
The exemplary aircraft system 5 has a fuel storage system 10 for storing one or more types of fuels that are used in the propulsion system 100. The exemplary aircraft system 5 shown in
As further described later herein, the propulsion system 100 shown in
The exemplary aircraft system 5 shown in
The exemplary embodiment of the aircraft system 5 shown in
The propulsion system 100 comprises a gas turbine engine 101 that generates the propulsive thrust by burning a fuel in a combustor.
During operation, air flows axially through fan 103, in a direction that is substantially parallel to a central line axis 15 extending through engine 101, and compressed air is supplied to high pressure compressor 105. The highly compressed air is delivered to combustor 90. Hot gases (not shown in
During operation of the aircraft system 5 (See exemplary flight profile shown in
An aircraft and engine system, described herein, is capable of operation using two fuels, one of which may be a cryogenic fuel such as for example, LNG (liquefied natural gas), the other a conventional kerosene based jet fuel such as Jet-A, JP-8, JP-5 or similar grades available worldwide.
The Jet-A fuel system is similar to conventional aircraft fuel systems, with the exception of the fuel nozzles, which are capable of firing Jet-A and cryogenic/LNG to the combustor in proportions from 0-100%. In the embodiment shown in
The fuel tank will preferably operate at or near atmospheric pressure, but can operate in the range of 0 to 100 psig. Alternative embodiments of the fuel system may include high tank pressures and temperatures. The cryogenic (LNG) fuel lines running from the tank and boost pump to the engine pylons may have the following features: (i) single or double wall construction; (ii) vacuum insulation or low thermal conductivity material insulation; and (iii) an optional cryo-cooler to re-circulate LNG flow to the tank without adding heat to the LNG tank. The cryogenic (LNG) fuel tank can be located in the aircraft where a conventional Jet-A auxiliary fuel tank is located on existing systems, for example, in the forward or aft cargo hold. Alternatively, a cryogenic (LNG) fuel tank can be located in the center wing tank location. An auxiliary fuel tank utilizing cryogenic (LNG) fuel may be designed so that it can be removed if cryogenic (LNG) fuel will not be used for an extended period of time.
A high pressure pump may be located in the pylon or on board the engine to raise the pressure of the cryogenic (LNG) fuel to levels sufficient to inject fuel into the gas turbine combustor. The pump may or may not raise the pressure of the LNG/cryogenic liquid above the critical pressure (Pc) of cryogenic (LNG) fuel. A heat exchanger, referred to herein as a “vaporizer,” which may be mounted on or near the engine, adds thermal energy to the liquefied natural gas fuel, raising the temperature and volumetrically expanding the cryogenic (LNG) fuel. Heat (thermal energy) from the vaporizer can come from many sources. These include, but are not limited to: (i) the gas turbine exhaust; (ii) compressor intercooling; (iii) high pressure and/or low pressure turbine clearance control air; (iv) LPT pipe cooling parasitic air; (v) cooled cooling air from the HP turbine; (vi) lubricating oil; or (vii) on board avionics or electronics. The heat exchanger can be of various designs, including shell and tube, double pipe, fin plate, etc., and can flow in a co-current, counter current, or cross current manner. Heat exchange can occur in direct or indirect contact with the heat sources listed above.
A control valve is located downstream of the vaporizer/heat exchange unit described above. The purpose of the control valve is to meter the flow to a specified level into the fuel manifold across the range of operational conditions associated with the gas turbine engine operation. A secondary purpose of the control valve is to act as a back pressure regulator, setting the pressure of the system above the critical pressure of cryogenic (LNG) fuel.
A fuel manifold is located downstream of the control valve, which serves to uniformly distribute gaseous fuel to the gas turbine fuel nozzles. In some embodiments, the manifold can optionally act as a heat exchanger, transferring thermal energy from the core cowl compartment or other thermal surroundings to the cryogenic/LNG/natural gas fuel. A purge manifold system can optionally be employed with the fuel manifold to purge the fuel manifold with compressor air (CDP) when the gaseous fuel system is not in operation. This will prevent hot gas ingestion into the gaseous fuel nozzles due to circumferential pressure variations. Optionally, check valves in or near the fuel nozzles can prevent hot gas ingestion.
An exemplary embodiment of the system described herein may operate as follows: Cryogenic (LNG) fuel is located in the tank at about 15 psia and about −265° F. It is pumped to approximately 30 psi by the boost pump located on the aircraft. Liquid cryogenic (LNG) fuel flows across the wing via insulated double walled piping to the aircraft pylon where it is stepped up to about 100 to 1,500 psia and can be above or below the critical pressure of natural gas/methane. The cryogenic (LNG) fuel is then routed to the vaporizer where it volumetrically expands to a gas. The vaporizer may be sized to keep the Mach number and corresponding pressure losses low. Gaseous natural gas is then metered though a control valve and into the fuel manifold and fuel nozzles where it is combusted in an otherwise standard aviation gas turbine engine system, providing thrust to the airplane. As cycle conditions change, the pressure in the boost pump (about 30 psi for example) and the pressure in the HP pump (about 1,000 psi for example) are maintained at an approximately constant level. Flow is controlled by the metering valve. The variation in flow in combination with the appropriately sized fuel nozzles result in acceptable and varying pressures in the manifold.
The exemplary aircraft system 5 has a fuel delivery system for delivering one or more types of fuels from the storage system 10 for use in the propulsion system 100. For a conventional liquid fuel such as, for example, a kerosene based jet fuel, a conventional fuel delivery system may be used. The exemplary fuel delivery system described herein, and shown schematically in
The exemplary fuel system 50 has a boost pump 52 such that it is in flow communication with the cryogenic fuel tank 122. During operation, when cryogenic fuel is needed in the dual fuel propulsion system 100, the boost pump 52 removes a portion of the cryogenic liquid fuel 112 from the cryogenic fuel tank 122 and increases its pressure to a second pressure “P2” and flows it into a wing supply conduit 54 located in a wing 7 of the aircraft system 5. The pressure P2 is chosen such that the liquid cryogenic fuel maintains its liquid state (L) during the flow in the supply conduit 54. The pressure P2 may be in the range of about 30 psia to about 40 psia. Based on analysis using known methods, for LNG, 30 psia is found to be adequate. The boost pump 52 may be located at a suitable location in the fuselage 6 of the aircraft system 5. Alternatively, the boost pump 52 may be located close to the cryogenic fuel tank 122. In other embodiments, the boost pump 52 may be located inside the cryogenic fuel tank 122. In order to substantially maintain a liquid state of the cryogenic fuel during delivery, at least a portion of the wing supply conduit 54 is insulated. In some exemplary embodiments, at least a portion of the conduit 54 has a double wall construction. The conduits 54 and the boost pump 52 may be made using known materials such as titanium, Inconel, aluminum or composite materials.
The exemplary fuel system 50 has a high-pressure pump 58 that is in flow communication with the wing supply conduit 54 and is capable of receiving the cryogenic liquid fuel 112 supplied by the boost pump 52. The high-pressure pump 58 increases the pressure of the liquid cryogenic fuel (such as, for example, LNG) to a third pressure “P3” sufficient to inject the fuel into the propulsion system 100. The pressure P3 may be in the range of about 100 psia to about 1000 psia. The high-pressure pump 58 may be located at a suitable location in the aircraft system 5 or the propulsion system 100. The high-pressure pump 58 is preferably located in a pylon 55 of aircraft system 5 that supports the propulsion system 100.
As shown in
The cryogenic fuel delivery system 50 comprises a flow metering valve 65 (“FMV”, also referred to as a Control Valve) that is in flow communication with the vaporizer 60 and a manifold 70. The flow metering valve 65 is located downstream of the vaporizer/heat exchange unit described above. The purpose of the FMV (control valve) is to meter the fuel flow to a specified level into the fuel manifold 70 across the range of operational conditions associated with the gas turbine engine operation. A secondary purpose of the control valve is to act as a back pressure regulator, setting the pressure of the system above the critical pressure of the cryogenic fuel such as LNG. The flow metering valve 65 receives the gaseous fuel 13 supplied from the vaporizer and reduces its pressure to a fourth pressure “P4”. The manifold 70 is capable of receiving the gaseous fuel 13 and distributing it to a fuel nozzle 80 in the gas turbine engine 101. In a preferred embodiment, the vaporizer 60 changes the cryogenic liquid fuel 112 into the gaseous fuel 13 at a substantially constant pressure.
The cryogenic fuel delivery system 50 further comprises a plurality of fuel nozzles 80 located in the gas turbine engine 101. The fuel nozzle 80 delivers the gaseous fuel 13 into the combustor 90 for combustion. The fuel manifold 70, located downstream of the control valve 65, serves to uniformly distribute gaseous fuel 13 to the gas turbine fuel nozzles 80. In some embodiments, the manifold 70 can optionally act as a heat exchanger, transferring thermal energy from the propulsion system core cowl compartment or other thermal surroundings to the LNG/natural gas fuel. In one embodiment, the fuel nozzle 80 is configured to selectively receive a conventional liquid fuel (such as the conventional kerosene based liquid fuel) or the gaseous fuel 13 generated by the vaporizer from the cryogenic liquid fuel such as LNG. In another embodiment, the fuel nozzle 80 is configured to selectively receive a liquid fuel and the gaseous fuel 13 and configured to supply the gaseous fuel 13 and a liquid fuel to the combustor 90 to facilitate co-combustion of the two types of fuels. In another embodiment, the gas turbine engine 101 comprises a plurality of fuel nozzles 80 wherein some of the fuel nozzles 80 are configured to receive a liquid fuel and some of the fuel nozzles 80 are configured to receive the gaseous fuel 13 and arranged suitably for combustion in the combustor 90.
In another embodiment of the present invention, fuel manifold 70 in the gas turbine engine 101 comprises an optional purge manifold system to purge the fuel manifold with compressor air, or other air, from the engine when the gaseous fuel system is not in operation. This will prevent hot gas ingestion into the gaseous fuel nozzles due to circumferential pressure variations in the combustor 90. Optionally, check valves in or near the fuel nozzles can be used prevent hot gas ingestion in the fuel nozzles or manifold.
In an exemplary dual fuel gas turbine propulsion system described herein that uses LNG as the cryogenic liquid fuel is described as follows: LNG is located in the tank 22, 122 at 15 psia and −265° F. It is pumped to approximately 30 psi by the boost pump 52 located on the aircraft. Liquid LNG flows across the wing 7 via insulated double walled piping 54 to the aircraft pylon 55 where it is stepped up to 100 to 1,500 psia and may be above or below the critical pressure of natural gas/methane. The Liquefied Natural Gas is then routed to the vaporizer 60 where it volumetrically expands to a gas. The vaporizer 60 is sized to keep the Mach number and corresponding pressure losses low. Gaseous natural gas is then metered though a control valve 65 and into the fuel manifold 70 and fuel nozzles 80 where it is combusted in an dual fuel aviation gas turbine system 100, 101, providing thrust to the aircraft system 5. As cycle conditions change, the pressure in the boost pump (30 psi) and the pressure in the HP pump 58 (1,000 psi) are maintained at an approximately constant level. Flow is controlled by the metering valve 65. The variation in flow in combination with the appropriately sized fuel nozzles result in acceptable and varying pressures in the manifold.
The dual fuel system consists of parallel fuel delivery systems for kerosene based fuel (Jet-A, JP-8, JP-5, etc) and a cryogenic fuel (LNG for example). The kerosene fuel delivery is substantially unchanged from the current design, with the exception of the combustor fuel nozzles, which are designed to co-fire kerosene and natural gas in any proportion. As shown in
III. A Fuel Storage System
The exemplary aircraft system 5 shown in
The exemplary cryogenic fuel storage system 10 shown in
The fuel storage system 10 may further comprise a safety release system 45 adapted to vent any high pressure gases that may be formed in the cryogenic fuel tank 22. In one exemplary embodiment, shown schematically in
The cryogenic fuel tank 22 may have a single wall construction or a multiple wall construction. For example, the cryogenic fuel tank 22 may further comprise (See
The cryogenic fuel storage system 10 shown in
According to an embodiment of the invention, foam stabilizers may be added to the cryogenic fuel delivery system 50 to minimize pressure pulses and flow instabilities in the fluid circuits allowing safe engine operation and enhanced system life. Foam stabilizers may also improve the vaporization stability of the LNG mixture by keeping the boiling process out of the film-boiling regime and by creating a pressure loss mechanism to isolate the upstream pump from the downstream fuel nozzles.
Typically, foam stabilizers may be positioned in transfer lines and in components in which it is beneficial to minimize pressure pulses and flow instabilities. The foam stabilizers of embodiments of the invention may be used in single or dual fuel engines.
In general, the foam stabilizers may include, but are not limited to solid materials having an open or closed cellular structure that have a large volume fraction of gas-filled pores. The pores may form an interconnected network that allows fluids to pass through it. The high surface area and turbulence created by the ligament structures of the foams may prevent or reduce the formation of a vapor film along the walls of a fluid passage.
Foam stabilizers may include, but are not limited to metal or composite materials, or a combination thereof. Metal foam stabilizers typically have high porosity that allows for a very lightweight material. For example, metals including, but not limited to aluminum, titanium, and tantalum may be used as foam stabilizers. According to an embodiment of the invention, foam stabilizers may be constructed by braising sheets of metal on either side of the foam, thereby creating a fluid passage for LNG.
The density and pore size of the foam stabilizer may be varied to achieve optimum system performance. For example, a foam stabilizer according to embodiments of the invention may have a density of about 0.1 to about 1.5 g/cm3 or about 0.4 to about 0.9 g/cm3. The pore size of the foam stabilizer may be about 0.5 to about 15 mm or about 1 to about 8 mm.
The exemplary operation of the fuel storage system, its components including the fuel tank, and exemplary sub systems and components is described as follows.
Natural gas exists in liquid form (LNG) at temperatures of approximately about −260° F. and atmospheric pressure. To maintain these temperatures and pressures on board a passenger, cargo, military, or general aviation aircraft, the features identified below, in selected combinations, allow for safe, efficient, and cost effective storage of LNG. Referring to
(A) A fuel tank 21, 22 constructed of alloys such as, but not limited to, aluminum AL 5456 and higher strength aluminum AL 5086 or other suitable alloys.
(B) A fuel tank 21, 22 constructed of light weight composite material.
(C) The above tanks 21, 22 with a double wall vacuum feature for improved insulation and greatly reduced heat flow to the LNG fluid. The double walled tank also acts as a safety containment device in the rare case where the primary tank is ruptured.
(D) An alternative embodiment of either the above utilizing lightweight insulation 27, such as, for example, Aerogel, to minimize heat flow from the surroundings to the LNG tank and its contents. Aerogel insulation can be used in addition to, or in place of a double walled tank design.
(E) An optional vacuum pump 28 designed for active evacuation of the space between the double walled tank. The pump can operate off of LNG boil off fuel, LNG, Jet-A, electric power or any other power source available to the aircraft.
(F) An LNG tank with a cryogenic pump 31 submerged inside the primary tank for reduced heat transfer to the LNG fluid. It is contemplated that the pump may be driven by an electric motor, which is co-located with the pump inside the tank; electric motor losses may be dissipated within the LNG, thereby helping to pressure the tank with additional boil off.
(G) An LNG tank with one or more drain lines 36 capable of removing LNG from the tank under normal or emergency conditions. The LNG drain line 36 is connected to a suitable cryogenic pump to increase the rate of removal beyond the drainage rate due to the LNG gravitational head.
(H) An LNG tank with one or more vent lines 41 for removal of gaseous natural gas, formed by the absorption of heat from the external environment. This vent line 41 system maintains the tank at a desired pressure by the use of a 1 way relief valve or back pressure valve 39.
(I) An LNG tank with a parallel safety relief system 45 to the main vent line, should an overpressure situation occur. A burst disk is an alternative feature or a parallel feature 46. The relief vent would direct gaseous fuel overboard.
A similar parallel safety relief system 47 may be installed for the vacuum-insulating space enveloping the cryogenic fuel tank in the event that the tank wall might rupture, thereby spilling fuel inventory into the vacuum space and flash vaporizing the spilled fuel such that a catastrophic overpressure pulse could result if the additional safety relief system were otherwise absent.
(J) An LNG fuel tank, with some or all of the design features above, whose geometry is designed to conform to the existing envelope associated with a standard Jet-A auxiliary fuel tank such as those designed and available on commercially available aircrafts.
(K) An LNG fuel tank, with some or all of the design features above, whose geometry is designed to conform to and fit within the lower cargo hold(s) of conventional passenger and cargo aircraft such as those found on commercially available aircrafts.
(L) Modifications to the center wing tank 22 of an existing or new aircraft to properly insulate the LNG, tank, and structural elements.
(M) An LNG fuel tank, with some or all of the design features above, whose geometry is designed to conform to and fit within chines, wing-mounted pods, or other aerodynamic structures external to the airframe of military aircraft or helicopters.
Venting and boil off systems are designed using known methods. Boil off of LNG is an evaporation process, which absorbs energy and cools the tank and its contents. Boil off LNG can be utilized and/or consumed by a variety of different processes, in some cases providing useful work to the aircraft system, in other cases, simply combusting the fuel for a more environmentally acceptable design. For example, vent gas from the LNG tank consists primarily of methane and is used for any or all combinations of the following:
(A) Routing to the Aircraft APU (Auxiliary Power Unit) 180. As shown in
(B) Routing to one or more aircraft gas turbine engine(s) 101. As shown in
(C) Flared. As shown in
(D) Vented. As shown in
(E) Ground operation. As shown in
IV. Propulsion (Engine) System
The vaporizer 60, shown schematically in
Heat exchange in the vaporizer 60 can occur in direct manner between the cryogenic fuel and the heating fluid, through a metallic wall.
(V) Method of Operating Dual Fuel Aircraft System
An exemplary method of operation of the aircraft system 5 using a dual fuel propulsion system 100 is described as follows with respect to an exemplary flight mission profile shown schematically in
An exemplary method of operating a dual fuel propulsion system 100 using a dual fuel gas turbine engine 101 comprises the following steps of: starting the aircraft engine 101 (see A-B in
In the exemplary method of operating the dual fuel aircraft gas turbine engine 101, the step of vaporizing the second fuel 12 may be performed using heat from a hot gas extracted from a heat source in the engine 101. As described previously, in one embodiment of the method, the hot gas may be compressed air from a compressor 155 in the engine (for example, as shown in
The exemplary method of operating a dual fuel aircraft engine 101, may, optionally, comprise the steps of using a selected proportion of the first fuel 11 and a second fuel 12 during selected portions of a flight profile 120, such as shown, for example, in
The exemplary method of operating a dual fuel aircraft engine 101 described above may further comprise the step of controlling the amounts of the first fuel 11 and the second fuel 12 introduced into the combustor 90 using a control system 130. An exemplary control system 130 is shown schematically in
The control system 130, 357 architecture and strategy is suitably designed to accomplish economic operation of the aircraft system 5. Control system feedback to the boost pump 52 and high pressure pump(s) 58 can be accomplished via the Engine FADEC 357 or by distributed computing with a separate control system that may, optionally, communicate with the Engine FADEC and with the aircraft system 5 control system through various available data busses.
The control system, such as for example, shown in
In an exemplary control system 130, 357, the control system software may include any or all of the following logic: (A) A control system strategy that maximizes the use of the cryogenic fuel such as, for example, LNG, on takeoff and/or other points in the envelope at high compressor discharge temperatures (T3) and/or turbine inlet temperatures (T41); (B) A control system strategy that maximizes the use of cryogenic fuel such as, for example, LNG, on a mission to minimize fuel costs; (C) A control system 130, 357 that re-lights on the first fuel, such as, for example, Jet-A, only for altitude relights; (D) A control system 130, 357 that performs ground starts on conventional Jet-A only as a default setting; (E) A control system 130, 357 that defaults to Jet-A only during any non typical maneuver; (F) A control system 130, 357 that allows for manual (pilot commanded) selection of conventional fuel (like Jet-A) or cryogenic fuel such as, for example, LNG, in any proportion; (G) A control system 130, 357 that utilizes 100% conventional fuel (like Jet-A) for all fast accels and decels.
The exterior 512 of the panel 504 may be an impermeable shell 512. The interior of the panel 504 may be a semi-hollow cavity with the capacity to contain fuel under pressure and direct it from the liquid inlet to the gaseous exhaust. It could be filled with and/or bonded to foamed metal 514, baffles 516, or some other structure or material(s) that react to the fuel pressure forces from one surface to the other maintaining the panel shape and integrity (as shown more clearly in
Attachment methods could utilize the turbine rear frame struts, centerbody, and exhaust nozzle surfaces.
The exterior of the panel 504 could be smooth and flat or could be modified to enhance heat transfer to the exhaust gas by adding fins, texture, devices to trip the boundary layer flow, or by twisting or curving the panel surface in such a way to redirect the exhaust gas flow.
The vaporizer could be limited to one panel 504 behind one turbine rear frame strut 510 or it could include multiple panels 504 behind multiple turbine rear frame struts 510. These panels 504 could be independent, connected in parallel, in series, or with bypass valves to allow flow through some panels while others have no fuel flowing through them, thus regulating the vaporized gas temperature.
Placing the vaporizer panels 504 in the aerodynamic wake of the turbine rear frame struts 510 solves the problem of high drag aerodynamic losses when the vaporizer is installed in the exhaust system. The inclusion of internally bonded baffles 516 or foamed metal 514 allows the vaporizer to be thin and light weight while being able to handle the internal fuel. The foamed metal internal structure ensures stable vaporization, a major problem in vaporization systems.
The low aero loss vaporizer solution described by this invention offers a significant improvement in SFC over other vaporizer solutions that obstruct the exhaust flow due to the associated drag penalty. The technology of the foamed metal core bonded to the exterior thin metal envelope allows inherently stable vaporization in a light weight, self-supporting structure.
The present disclosure contemplates that, in some circumstances, it may be disadvantageous to supply certain liquid fuels (e.g., liquid natural gas, liquid hydrogen) to the combustor nozzles (also referred to as “fuel nozzles”) in a liquid form using current nozzle designs. Vaporizing such fuels prior to injection into the combustor may allow the fuels to ignite and burn more effectively.
The present disclosure contemplates that some vaporization systems may use a heavy intermediate fluid system to extract heat from other areas of the engine. Some example embodiments according to at least some aspects of the present disclosure may not require the use of an intermediate fluid system.
Some example embodiments according to at least some aspects of the present disclosure may relate to methods and apparatus for vaporizing a liquid fuel using the combustor and/or associated components of a jet engine as the heat source. In some example embodiments, heat from the combustion area (e.g., combustor 90 and/or combustor case (both shown in
An example vaporizer may be a separate component mounted externally to the combustor case (e.g., to an exterior surface of the combustor case wall), a separate component mounted inside the combustor case (e.g., to an interior surface of the combustor case wall), and/or vaporizer passages may be manufactured integrally with the combustor case wall.
Generally, as liquid fuel is supplied to the inlet of the vaporizer, heat absorbed into the vaporizer from the combustion process may heat and/or boil the liquid fuel until it emerges from the vaporizer exit (e.g., as a gas). In some example embodiments, the gaseous fuel may be supplied to the combustor fuel nozzles.
The present disclosure contemplates that, typically, the combustor may be one of the hottest parts of the engine. A vaporizer disposed at or near the combustor may require less surface area to absorb a given amount of energy than at other locations in or on the engine. Accordingly, a vaporizer configured for mounting at or near the combustor may be able to be sized smaller and/or lighter than a vaporizer configured for mounting at a lower-temperature location.
Although
Although
The following is a non-exhaustive list of potential points of novelty: A fuel vaporizer disposed in heat transfer communication with a combustor of a gas turbine engine. A fuel vaporizer disposed in heat transfer communication with a combustor case wall of the gas turbine engine. A fuel vaporizer arranged to vaporize a liquid fuel flowing there through by transferring heat from a combustor to the fuel. A fuel vaporizer mounted within a combustor case on an interior surface of the combustor case wall. A fuel vaporizer mounted on an exterior surface of a combustor case wall. A fuel vaporizer integrally formed with a combustor case wall.
The illustrated example is not meant to be limiting of a vaporizer/heat exchanger that is capable of transferring heat to a fluid (with or without phase change, liquid to gas) that is routed through the vaporizer 60 and that uses compressor discharge gases of the aircraft engine. The vaporizer 60 may include embodiments that provide coiled, all axial, and/or a combination (coiled and axial) of tubes selected as desired to accomplish a desired heat transfer requirement to the fluid. Alternatives provide that the vaporizer/heat exchanger may be integral to the compressor case itself. Embodiments of the vaporizer 60 may be manufactured from materials to include metal, composite, or a combination thereof.
Utilization of the embodiments and alternatives herein provide for a variety of single and dual fuel engines for which the with the exhaust gasses are a heat source to bring the fuel temperature to system and/or combustion requirements while also achieving a minimal increase to specific fuel consumption.
With reference to
With respect to
During operation, the heat exchanger 714 changes the phase of the natural gas while the second heat exchanger 712 utilizes a lower temperature air sink to operate as a recuperater to lower or raise the temperature, as desired, of the vaporized liquid gas. For example, the second heat exchanger 712 may lower the temperature at low LNG flow rates or, alternatively, raise the temperature at high LNG flow rates.
Conversely, in
The above described embodiments allow for the utilization of different heat sinks for vaporization of liquid natural gas in an aircraft engine. The multistage vaporizer systems not only vaporize the liquid natural gas but also control its temperature. In the art, temperature control of the vaporized LNG is a challenge not overcome until the creation of the present embodiments. Before now, if a heat exchanger was sized to provide the vaporization required at high engine demand LNG flow rates then the fuel would have likely been over temped at lower engine demand LNG flow rates. Prior art designs further require that active control using a bypass system and valving is provided. Such prior art actively controlled designs are complex and add weight to the system. The prior art challenge of existing designs is overcome by the present embodiments in that no control system is required to ensure that the temperature fuel is within spec. Instead, embodiments for this passively controlled and therefore simpler system dispense with a need for extra valving. There are also some potential weight advantages for putting the lower temperature heat sink first in that it could enable the use of lower density materials such as aluminum.
Embodiments are provided for heating a fluid such as fuel in the form of liquid natural gas from cold temperatures to the required system and/or combustion temperatures with the exhaust gasses of airplane engines including turbo-fan, turbo-jet, turbo-prop, open-rotor, etc. As desired, embodiments provide that the fluid may undergo a phase change from liquid to gas in the heating as well as embodiments for which the fluid remains in a single phase. The phase may be selected from the group including liquid or gas. As such, embodiments and alternatives are provided that allow single or dual fuel combustion for airplane engines.
Exemplary embodiments include vaporizer/heat exchangers that are able to transfer heat to a fluid, with or without phase change from liquid to gas, in the exhaust gases of airplane engines. With reference to
With reference to
It will be understood that while the dual fuel system has been described and illustrated as including a first fuel system independent from the second fuel system that the dual fuel system may be structured in any suitable manner. For example, portions of the first and second fuel systems may be combined in any suitable manner, which may reduce the weight. By way of non-limiting example, such a system may include that the fuels may be mixed in one supply system. For example, the fuels may be mixed as a liquid, vaporized, and the resulting mixture may be supplied out of a single port fuel nozzle.
To the extent not already described, the different features and structures of the various embodiments may be used in combination with each other as desired. That one feature may not be illustrated in all of the embodiments is not meant to be construed that it may not be, but is done for brevity of description. Thus, the various features of the different embodiments may be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
Claims
1. A turbine engine assembly comprising:
- a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned, wherein the combustion section comprises a generally annular case having inner and outer walls;
- a heat exchanger comprising multiple passages in proximity to at least one of the inner and outer walls, with the passages arranged about at least a portion of the case and in fluid communication with each other such that fluid may flow through the passages; and
- a cryogenic fuel system having a cryogenic fuel tank with a supply line coupled to one of the passages, wherein cryogenic fuel may be supplied from the cryogenic fuel tank, through the supply line, to the passages of the heat exchanger, where the fuel in the passages may be heated by the combustion section.
2. The turbine engine assembly of claim 1 wherein the passages extend substantially about the annular case.
3. The turbine engine assembly of claim 1 wherein the passages are adjacent the outer wall.
4. The turbine engine assembly of claim 1 wherein the passages are adjacent the inner wall.
5. The turbine engine assembly of claim 1 wherein the passages are between the inner and outer wall.
6. The turbine engine assembly of claim 1 wherein the turbine core defines a central axis and the passages are generally aligned with the central axis.
7. The turbine engine assembly of claim 1 wherein each of the passages have an inlet and outlet.
8. The turbine engine assembly of claim 7, further comprising a header fluidly coupling the inlet and outlet of adjacent passages.
9. A turbine engine assembly comprising:
- a turbine core comprising a compressor section, a combustion section, a turbine section, and a nozzle section, which are axially aligned;
- a cryogenic fuel system having a cryogenic fuel tank with a supply line; and
- a multistage vaporizer comprising at least one passage fluidly coupled with the supply line such that cryogenic fuel supplied from the cryogenic fuel tank may flow through the at least one passage of the multistage vaporizer, where the fuel in the at least one passage may be heated.
10. The turbine engine assembly of claim 9 wherein at least one stage of the multistage vaporizer comprises a hot air engine sink utilizing hot air selected from a group comprising compressor air, core exhaust air, and turbine bleed air.
11. The turbine engine assembly of claim 9 wherein the multistage vaporizer comprises a first heat exchanger and a second heat exchanger in parallel.
12. The turbine engine assembly of claim 11, further comprising a split valve for directing portions of the cryogenic fuel to the first heat exchanger and the second heat exchanger.
13. The turbine engine assembly of claim 9 wherein the multistage vaporizer comprise a first heat exchanger and a second heat exchanger in series.
14. The turbine engine assembly of claim 13 wherein the first heat exchanger utilizes hot air at a first temperature to heat the cryogenic fuel and the second heat exchanger utilizes hot air at a temperature different than the first temperature.
15. The turbine engine assembly of claim 9 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
16. The turbine engine assembly of claim 10 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
17. The turbine engine assembly of claim 11 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
18. The turbine engine assembly of claim 12 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
19. The turbine engine assembly of claim 13 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
20. The turbine engine assembly of claim 14 wherein the cryogenic fuel in the cryogenic fuel tank is liquefied natural gas.
Type: Application
Filed: Nov 26, 2013
Publication Date: Nov 26, 2015
Inventors: Thomas KUPISZEWSKI (Cincinnati, OH), Michael Jay EPSTEIN (Cincinnati, OH), Todd James BUCHHOLZ (Cincinnati, OH), Adon DELGADO (Cincinnati, OH), Christopher Dale MATHIAS (Cicninnati, OH), Deborah Ann OAKES (Cincinnati, OH)
Application Number: 14/655,769